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US10241431B2 - Toner - Google Patents
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US10241431B2 - Toner - Google Patents

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US10241431B2
US10241431B2 US15/806,422 US201715806422A US10241431B2 US 10241431 B2 US10241431 B2 US 10241431B2 US 201715806422 A US201715806422 A US 201715806422A US 10241431 B2 US10241431 B2 US 10241431B2
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Prior art keywords
toner
mass
crystalline polyester
styrene
resin
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US15/806,422
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US20180149991A1 (en
Inventor
Kohei YAMAUCHI
Hiroki Uemura
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Kyocera Document Solutions Inc
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Kyocera Document Solutions Inc
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Assigned to KYOCERA DOCUMENT SOLUTIONS INC. reassignment KYOCERA DOCUMENT SOLUTIONS INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: UEMURA, HIROKI, YAMAUCHI, KOHEI
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/087—Binders for toner particles
    • G03G9/08775—Natural macromolecular compounds or derivatives thereof
    • G03G9/08782—Waxes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/0819—Developers with toner particles characterised by the dimensions of the particles
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/0821—Developers with toner particles characterised by physical parameters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/087—Binders for toner particles
    • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/08706—Polymers of alkenyl-aromatic compounds
    • G03G9/08708—Copolymers of styrene
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/087—Binders for toner particles
    • G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/08706—Polymers of alkenyl-aromatic compounds
    • G03G9/08708—Copolymers of styrene
    • G03G9/08711—Copolymers of styrene with esters of acrylic or methacrylic acid
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/087—Binders for toner particles
    • G03G9/08742—Binders for toner particles comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G9/08755—Polyesters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/08—Developers with toner particles
    • G03G9/087—Binders for toner particles
    • G03G9/08784—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775
    • G03G9/08797—Macromolecular material not specially provided for in a single one of groups G03G9/08702 - G03G9/08775 characterised by their physical properties, e.g. viscosity, solubility, melting temperature, softening temperature, glass transition temperature

Definitions

  • the present disclosure relates to a toner.
  • toner particles contain a non-crystalline polyester resin, a crystalline polyester resin, and a styrene-acrylic acid resin.
  • a toner according to the present disclosure includes a plurality of toner particles containing a non-crystalline polyester resin and an ester wax.
  • the toner particles further contain at least 10 parts by mass and no greater than 30 parts by mass of a crystalline polyester resin and at least 30 parts by mass and no greater than 50 parts by mass of a styrene-acrylic acid-based resin relative to 100 parts by mass of the non-crystalline polyester resin.
  • the crystalline polyester resin includes a first repeating unit derived from an acrylic acid-based monomer and a second repeating unit derived from a styrene-based monomer.
  • the styrene-acrylic acid-based resin includes a third repeating unit derived from an acrylic acid-based monomer having an amino group and a fourth repeating unit derived from a styrene-based monomer.
  • An intensity of a peak from an amino group of the third repeating unit is at least 40% and no greater than 60% of an intensity of a peak from an aromatic ring of the fourth repeating unit on an FT-IR spectrum of the toner measured by an attenuated total reflection (ATR) method.
  • An amount of the ester wax in the toner particles is at least 8 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the non-crystalline polyester resin.
  • the ester wax in the toner particles has a dispersion diameter of at least 500 nm and no greater than 1,000 nm.
  • FIG. is a spectral chart showing an FT-IR spectrum measured with respect to a toner according to an embodiment of the present disclosure.
  • Evaluation results for example, values indicating a shape and physical properties
  • a powder specifically examples include toner mother particles, an external additive, and a toner
  • evaluation results are each a number average of values measured for a suitable number of average particles selected from the particles included in the powder, unless otherwise stated.
  • a number average particle diameter of a powder is a number average of equivalent circle diameters of primary particles (Heywood diameters: diameters of circles having the same area as projections of the particles) measured using a microscope, unless otherwise stated.
  • a value for volume median diameter (D 50 ) of a powder is measured using a laser diffraction/scattering particle size distribution analyzer (“LA-750”, product of Horiba, Ltd.), unless otherwise stated. Acid values and hydroxyl values are measured in accordance with “Japanese Industrial Standard (JIS) K0070-1992”, unless otherwise stated. Values for number average molecular weight (Mn) and mass average molecular weight (Mw) are measured by gel permeation chromatography, unless otherwise stated.
  • a value for a glass transition point (Tg) is measured in accordance with “Japanese Industrial Standard (JIS) K7121-2012” using a differential scanning calorimeter (“DSC-6220”, product of Seiko Instruments Inc.), unless otherwise stated.
  • DSC-6220 differential scanning calorimeter
  • the glass transition point (Tg) corresponds to a temperature (onset temperature) at a point of change in specific heat (i.e., an intersection point of an extrapolation line of a base line and an extrapolation line of an inclined portion of the curve).
  • a value for a softening point (Tm) is measured using a capillary rheometer (“CFT-500D”, product of Shimadzu Corporation), unless otherwise stated.
  • CFT-500D capillary rheometer
  • the softening point (Tm) is a temperature corresponding to a stroke value of “(base line stroke value+maximum stroke value)/2”.
  • a value for a melting point is a temperature of a peak indicating maximum heat absorption on a heat absorption curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) measured using a differential scanning calorimeter (“DSC-6220”, product of Seiko Instruments Inc.), unless otherwise stated.
  • chargeability refers to chargeability in triboelectric charging, unless otherwise stated.
  • Strength of positive chargeability (or strength of negative chargeability) in triboelectric charging can be confirmed by for example a known triboelectric series.
  • SP values are calculated (unit: (cal/cm 3 ) 1/2 , temperature: 25° C.) in accordance with the Fedors estimation method (R. F. Fedors, “Polymer Engineering Science”, 14(2), p 147-154 (1974)), unless otherwise stated.
  • the term “-based” may be appended to the name of a chemical compound in order to form a generic name encompassing both the chemical compound itself and derivatives thereof.
  • the term “-based” is appended to the name of a chemical compound used in the name of a polymer, the term indicates that a repeating unit of the polymer originates from the chemical compound or a derivative thereof.
  • the term “(meth)acryl” may be used as a generic term for both acryl and methacryl.
  • (meth)acrylonitrile” may be used as a generic term for both acrylonitrile and methacrylonitrile.
  • the toner according to the present embodiment is for example suitable for use as a positively chargeable toner for developing an electrostatic latent image.
  • the toner according to the present embodiment is a powder including a plurality of toner particles (particles each having the feature described below).
  • the toner may be used as a one-component developer.
  • a two-component developer may be prepared by mixing the toner and a carrier using a mixer (for example, a ball mill).
  • a ferrite carrier is preferably used as the carrier.
  • magnetic carrier particles including carrier cores and resin layers coating the carrier cores are preferably used.
  • carrier cores thereof may be formed from a magnetic material (for example, ferromagnetic material such as ferrite) or formed from a resin in which magnetic particles are dispersed.
  • magnetic particles may be dispersed in resin layers coating carrier cores thereof.
  • the amount of the toner in the two-component developer is at least 5 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the carrier in order to achieve high quality image formation. Note that a positively chargeable toner included in a two-component developer is positively charged by friction against a carrier therein.
  • the toner according to the present embodiment can for example be used in image formation in an electrophotographic apparatus (image forming apparatus).
  • image forming apparatus image forming apparatus
  • the following describes an example of image forming methods that are performed by electrophotographic apparatuses.
  • an image forming section (for example, a charger and a light exposure device) of an electrophotographic apparatus forms an electrostatic latent image on a photosensitive member (for example, on a surface of a photosensitive drum) based on image data.
  • a developing device (more specifically, a developing device having a toner-containing developer loaded therein) of the electrophotographic apparatus supplies the toner to the photosensitive member to develop the electrostatic latent image formed on the photosensitive member.
  • the toner is charged by friction with the carrier or a blade in the developing device before being supplied to the photosensitive member. For example, a positively chargeable toner is positively charged.
  • the toner (more specifically, the charged toner) on the development sleeve (for example, a surface of a development roller in the developing device) disposed in the vicinity of the photosensitive member is supplied to the photosensitive member and caused to adhere to the electrostatic latent image on the photosensitive member, so that a toner image is formed on the photosensitive member.
  • Toner is supplied to the developing device from a toner container containing toner for replenishment use to make up for consumed toner.
  • a transfer device of the electrophotographic apparatus transfers the toner image on the photosensitive member onto an intermediate transfer member (for example, a transfer belt), and then further transfers the toner image from the intermediate transfer member onto a recording medium (for example, paper).
  • a fixing device fixing method: nip fixing in which fixing is performed through a nip between a heating roller and a pressure roller
  • a full-color image can for example be formed by superimposing toner images of four different colors: black, yellow, magenta, and cyan.
  • a direct transfer process may alternatively be employed, which involves direct transfer of the toner image on the photosensitive member to the recording medium without the use of the intermediate transfer member.
  • a belt fixing process may alternatively be employed, in which fixing is performed using a belt.
  • the toner according to the present embodiment includes a plurality of toner particles.
  • the toner particles may include an external additive.
  • the toner particles each include the external additive
  • the toner particles each include a toner mother particle and the external additive.
  • the external additive adheres to the surfaces of the toner mother particles.
  • the toner mother particles contain a binder resin and a releasing agent.
  • the toner mother particles may contain, in addition to the binder resin and the releasing agent, optional internal additives (for example, at least one of a colorant, a charge control agent, and a magnetic powder).
  • the external additive may be omitted if unnecessary. In a situation in which the external additive is omitted, the toner mother particles are equivalent to the toner particles.
  • the toner particles included in the toner according to the present embodiment may be toner particles having no shell layers (hereinafter, referred to as non-capsule toner particles) or may be toner particles having shell layers (hereinafter, referred to as capsule toner particles).
  • a toner mother particle includes a toner core and a shell layer disposed over a surface of the toner core.
  • the shell layer is substantially composed of a resin. Both heat-resistant preservability and low-temperature fixability of the toner can be achieved for example by using low-melting toner cores and covering each core with a highly heat-resistant shell layer.
  • An additive may be dispersed in the resin forming the shell layer.
  • the shell layer may entirely cover the surface of each toner core or partially cover the surface of each toner core.
  • the shell layer may be substantially composed of a thermosetting resin, may be substantially composed of a thermoplastic resin, or may include both a thermoplastic resin and a thermosetting resin.
  • the non-capsule toner particles can for example be prepared by a pulverization method or an aggregation method. These methods facilitate sufficient dispersion of internal additives in the binder resin of the non-capsule toner particles. It is known in the art to which the present disclosure belongs that toners are broadly classified as being pulverized toners and as being polymerized toners (referred to also as chemical toner). Toners obtained by a pulverization method are classified as being pulverized toners. Toners obtained by an aggregation method are classified as being polymerized toners.
  • the binder resin, the colorant, the charge control agent, and the releasing agent are first mixed together.
  • the resultant mixture is melt-kneaded using a melt-kneader (for example, a single or twin screw extruder).
  • a melt-kneader for example, a single or twin screw extruder.
  • the resultant melt-knead product is pulverized, and the resultant pulverized product is classified.
  • toner mother particles are obtained.
  • the toner mother particles tend to be prepared more easily by the pulverization method than by the aggregation method.
  • fine particles of the binder resin, the releasing agent, the charge control agent, and the colorant are caused to aggregate in an aqueous medium containing the aforementioned fine particles until particles of a desired diameter are obtained.
  • aggregated particles of the binder resin, the releasing agent, the charge control agent, and the colorant are formed.
  • the aggregated particles are heated in order to cause components contained in the aggregated particles to coalesce. The above process yields toner mother particles having a desired particle diameter.
  • shell layers may be formed by any method.
  • the shell layers may be formed according to an in-situ polymerization process, an in-liquid curing film coating process, or a coacervation process.
  • the toner according to the present embodiment is an electrostatic latent image developing toner having the following feature (hereinafter, referred to as the basic feature).
  • the toner includes a plurality of toner particles containing a non-crystalline polyester resin and an ester wax.
  • the toner particles further contain at least 10 parts by mass and no greater than 30 parts by mass of a crystalline polyester resin and at least 30 parts by mass and no greater than 50 parts by mass of a styrene-acrylic acid-based resin relative to 100 parts by mass of the non-crystalline polyester resin.
  • the crystalline polyester resin includes a first repeating unit derived from an acrylic acid-based monomer and a second repeating unit derived from a styrene-based monomer.
  • the styrene-acrylic acid-based resin includes a third repeating unit derived from an acrylic acid-based monomer having an amino group and a fourth repeating unit derived from a styrene-based monomer.
  • the intensity of a peak (the height of a peak) from the amino group of the third repeating unit is at least 40% and no greater than 60% of the intensity of a peak (the height of a peak) from an aromatic ring of the fourth repeating unit.
  • the amount of the ester wax in the toner particles is at least 8 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the non-crystalline polyester resin.
  • the ester wax in the toner particles has a dispersion diameter of at least 500 nm and no greater than 1,000 nm.
  • a vinyl compound is a repeating unit that is formed into a resin by addition polymerization through carbon-to-carbon double bonds “C ⁇ C” (“C ⁇ C” ⁇ “—C—C—”).
  • the vinyl compound refers to a compound having a vinyl group (CH 2 ⁇ CH—) or a substituted vinyl group in which hydrogen is replaced.
  • vinyl compounds that can be used include ethylene, propylene, butadiene, vinyl chloride, acrylic acid, an acrylic acid ester, methacrylic acid, a methacrylic acid ester, acrylonitrile, and styrene.
  • the dispersion diameter of the ester wax in the toner particles refers to a number average of equivalent circle diameters of ester wax domains in cross-sectional images of the toner particles.
  • the ratio of the intensity of the peak from the amino group of the third repeating unit to the intensity of the peak from the aromatic ring of the fourth repeating unit on the FT-IR spectrum of the toner measured by the ATR method may be referred to as an amino group ratio.
  • the requirement that the amino group ratio is at least 40% and no greater than 60% is satisfied so long as the intensity of the peak from the amino group of the third repeating unit is at least 1.2% and no greater than 1.8%.
  • the FT-IR spectrum is measured by the same method as a method indicated in the Examples explained further below or according to an alternative thereof.
  • FIG. shows an example of the FT-IR spectrum of the toner having the above-described feature.
  • the FT-IR spectrum (vertical axis: transmittance, horizontal axis: wavenumber) shown in FIG. includes a peak P 1 from the amino group of the third repeating unit and a peak P 2 from the aromatic ring of the fourth repeating unit.
  • the toner particles contain a crystalline polyester resin and a non-crystalline polyester resin.
  • the toner particles containing a crystalline polyester resin the toner particles are sharp-melting.
  • the toner particles being sharp-melting, the toner tends to be excellent in both heat-resistant preservability and low-temperature fixability.
  • a toner whose toner particles contain a crystalline polyester resin tends to have reduced elasticity.
  • hot offset tends to easily occur, and pulverizing performance of the toner tends to be reduced.
  • a non-crystalline polyester resin having a low softening point (Tm) may be included in the toner particles.
  • Tm softening point
  • the toner particles including a non-crystalline polyester resin having a low softening point (Tm) the toner tends to have reduced low-temperature fixability.
  • the toner particles contain a styrene-acrylic acid-based resin in addition to a crystalline polyester resin and a non-crystalline polyester resin.
  • the present inventor has found that pulverizing performance of the toner can be improved by including a crystalline polyester resin, a non-crystalline polyester resin, and a styrene-acrylic acid-based resin in the toner particles. The reason for the above is thought to be that the toner including such toner particles has increased pulverizing interfaces.
  • the toner particles contain at least 10 parts by mass and no greater than 30 parts by mass of a crystalline polyester resin and at least 30 parts by mass and no greater than 50 parts by mass of a styrene-acrylic acid-based resin relative to 100 parts by mass of the non-crystalline polyester resin.
  • the toner particles containing each resin in an appropriate amount it is possible to improve pulverizing performance and low-temperature fixability of the toner while inhibiting insufficient dispersion of toner components (internal additives). If the amount of the crystalline polyester resin is too small, the toner tends to have poor low-temperature fixability.
  • the toner tends to have poor pulverizing performance. If the amount of the styrene-acrylic acid-based resin is too small, the toner tends to have poor pulverizing performance. If the amount of the styrene-acrylic acid-based resin is too large, dispersion of toner components (internal additives) tends to be insufficient.
  • the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin, which are commonly used as toner materials, are not compatible with one another.
  • the mere use of a combination of these three resins as a binder resin of the toner particles therefore easily leads to insufficient dispersion of toner components (internal additives). Insufficient dispersion of toner components tends to lead to poor low-temperature fixability of the toner.
  • the binder resin of the toner particles has an SP value of at least 9 and no greater than 12.
  • a crystalline polyester resin for example, a copolymer of an ⁇ , ⁇ -alkanediol and an ⁇ , ⁇ -alkanedicarboxylic acid
  • a non-crystalline polyester resin for example a polymer of a bisphenol and an aromatic dicarboxylic acid
  • a styrene-acrylic acid-based resin for example, a polymer of styrene and an acrylic acid ester
  • the crystalline polyester resin includes the first repeating unit derived from an acrylic acid-based monomer and the second repeating unit derived from a styrene-based monomer, and the styrene-acrylic acid-based resin includes the third repeating unit derived from an acrylic acid-based monomer having an amino group and the fourth repeating unit derived from a styrene-based monomer.
  • the amino group ratio in the styrene-acrylic acid-based resin is at least 40% and no greater than 60%.
  • each of the crystalline polyester resin and the styrene-acrylic acid-based resin includes a styrene-acrylic acid-based unit (the first and second repeating units in the crystalline polyester resin, and the third and fourth repeating units in the styrene-acrylic acid-based resin), and the amino group ratio in the styrene-acrylic acid-based resin is at least 40% and no greater than 60%, the SP value of the crystalline polyester resin, the SP value of the non-crystalline polyester resin, and the SP value of the styrene-acrylic acid-based resin are close to one another to an appropriate degree.
  • the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin being compatible with one another to an appropriate degree, it is possible to improve pulverizing performance of the toner while inhibiting insufficient dispersion of toner components (internal additives).
  • the amino group ratio in the styrene-acrylic acid-based resin increases, the SP value of the styrene-acrylic acid-based resin tends to increase, and compatibility between the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin tends to increase.
  • the SP value of the styrene-acrylic acid-based resin tends to decrease, and compatibility between the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin tends to decrease.
  • the present inventor has found that by including an ester wax in the toner particles in addition to the binder resin (the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin) as defined by the above-described basic feature, it is possible to achieve not only an appropriate degree of compatibility between the crystalline polyester resin, the non-crystalline polyester resin, and the styrene-acrylic acid-based resin but also an appropriate degree of compatibility between the binder resin and the releasing agent (ester wax).
  • the SP value of the binder resin and the SP value of the ester wax (releasing agent) are far from each other to an appropriate degree, and the ester wax (releasing agent) disperses in the toner particles to an appropriate degree, having an appropriate dispersion diameter.
  • the ester wax in the toner particles can have an appropriate dispersion diameter (more specifically, at least 500 nm and no greater than 1,000 nm).
  • the amino group ratio in the styrene-acrylic acid-based resin is too large, compatibility between the binder resin and the ester wax (releasing agent) tends to be insufficient, and the releasing agent tends to have a too large dispersion diameter. If the releasing agent has a too large dispersion diameter, the toner tends to easily aggregate during storage. If the amino group ratio in the styrene-acrylic acid-based resin is too small, compatibility between the binder resin and the ester wax (releasing agent) tends to be too high, and the releasing agent tends to have a too small dispersion diameter. If the releasing agent has a too small dispersion diameter, the toner tends to have insufficient hot offset resistance.
  • the amount of the ester wax in the toner particles is at least 8 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the non-crystalline polyester resin, and the dispersion diameter of the ester wax in the toner particles is at least 500 nm and no greater than 1,000 nm. It is possible to improve releasability of the toner (and thus improve hot offset resistance of the toner) by dispersing a sufficient amount of releasing agent (ester wax) in the toner particles such that the releasing agent has a sufficient dispersion diameter. If the amount of the releasing agent is too large or the releasing agent has a too large dispersion diameter, the releasing agent easily detaches from the toner particles. The detached releasing agent may cause aggregation of the toner during storage, and occurrence of fogging and contamination of the inside of the apparatus upon image formation.
  • the following describes a composition of the non-capsule toner particles. More specifically, the following describes, in order, toner mother particles (a binder resin and internal additives) and an external additive.
  • toner mother particles of the non-capsule toner particles can be used as toner cores for capsule toner particles.
  • the toner mother particles contain a binder resin and a releasing agent.
  • the toner mother particles may contain other internal additives (for example, a colorant, a charge control agent, and a magnetic powder).
  • the binder resin is typically a main component (for example, at least 85% by mass) of the toner mother particles. Accordingly, properties of the binder resin are thought to have a great influence on overall properties of the toner mother particles.
  • the toner mother particles have a higher tendency to be anionic in a situation in which the binder resin has, for example, an ester group, a hydroxyl group, an ether group, an acid group, or a methyl group, and have a higher tendency to be cationic in a situation in which the binder resin has, for example, an amino group.
  • the toner mother particles contain, as the binder resin, a crystalline polyester resin, a non-crystalline polyester resin, and a styrene-acrylic acid-based resin.
  • a polyester resin can be synthesized through polycondensation of at least one polyhydric alcohol with at least one polycarboxylic acid.
  • alcohols that can be preferably used in synthesis of the polyester resin include dihydric alcohols (specific examples include aliphatic diols and bisphenols) and tri- or higher-hydric alcohols listed below.
  • carboxylic acids that can be preferably used in synthesis of the polyester resin include di-, tri-, and higher-basic carboxylic acids listed below.
  • Examples of preferable aliphatic diols include diethylene glycol, triethylene glycol, neopentyl glycol, 1,2-propanediol, ⁇ , ⁇ -alkanediols (specific examples include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,12-dodecanediol), 2-butene-1,4-diol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.
  • Examples of preferable bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct.
  • Examples of preferable tri- or higher-hydric alcohols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl- 1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.
  • Examples of preferable dibasic carboxylic acids include aromatic dicarboxylic acids (specific examples include phthalic acid, terephthalic acid, and isophthalic acid), ⁇ , ⁇ -alkane dicarboxylic acids (specific examples include malonic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, and 1,10-decanedicarboxylic acid), alkyl succinic acids (specific examples include n-butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, n-dodecylsuccinic acid, and isododecylsuccinic acid), alkenyl succinic acids (specific examples include n-butenylsuccinic acid, isobutenylsuccinic acid, n-octenylsuccinic acid, n-dodecenylsuccinic acid, and iso
  • Examples of preferable tri- or higher-basic carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and EMPOL trimer acid.
  • the styrene-acrylic acid-based resin is a copolymer of at least one styrene-based monomer and at least one acrylic acid-based monomer.
  • examples of styrene-based monomers and acrylic acid-based monomers that can be preferably used for synthesis of the styrene-acrylic acid-based resin are listed below.
  • styrene-based monomers examples include styrene, alkylstyrenes (specific examples include ⁇ -methylstyrene, p-ethylstyrene, and 4-tert-butylstyrene), p-hydroxy styrene, m-hydroxy styrene, ⁇ -chlorostyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene.
  • alkylstyrenes specifically examples include ⁇ -methylstyrene, p-ethylstyrene, and 4-tert-butylstyrene
  • p-hydroxy styrene m-hydroxy styrene
  • ⁇ -chlorostyrene o-chlorostyrene
  • o-chlorostyrene m-chlorostyrene
  • m-chlorostyrene
  • Examples of preferable acrylic acid-based monomers include (meth)acrylic acid, (meth)acrylonitrile, alkyl (meth)acrylates, and hydroxyalkyl (meth)acrylates.
  • Examples of the alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.
  • hydroxyalkyl (meth)acrylates examples include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.
  • the non-crystalline polyester resin (the binder resin) is preferably a non-crystalline polyester resin containing 1,2-propanediol as the alcohol component, and is particularly preferably a polymer of 1,2-propanediol, at least one aromatic dicarboxylic acid (for example, terephthalic acid), and at least one tribasic carboxylic acid (for example, trimellitic acid).
  • a tri- or higher-basic carboxylic acid functions as a cross-linking agent.
  • the 1,2-propanediol that is particularly preferable for synthesis of the non-crystalline polyester resin (the binder resin) is plant-derived 1,2-propanediol.
  • the plant-derived 1,2-propanediol is for example produced through chemical synthesis, fermentation, or a combination of chemical synthesis and fermentation.
  • glycerin is obtained through hydrolysis of plant biomass including saccharides, such as glucose.
  • a reaction of glycerin and hydrogen is caused to yield plant-derived 1,2-propanediol.
  • Plant biomass that can be used is for example at least one vegetable oil selected from the group consisting of soya oil, coconut oil, palm oil, castor oil, and cocoa oil.
  • the plant biomass may be hydrolyzed by a chemical method using an acid or a base, by a biological method using enzyme or a microorganism, or by other methods.
  • the crystalline polyester resin includes the first repeating unit derived from an acrylic acid-based monomer and the second repeating unit derived from a styrene-based monomer.
  • the crystalline polyester resin (the binder resin) is a polymer of at least one ⁇ , ⁇ -alkanediol (for example, 1,4-butanediol and 1,6-hexanediol), at least one dibasic carboxylic acid (for example, fumaric acid), at least one styrene-based monomer (for example, styrene), and at least one alkyl (meth)acrylate (for example, n-butyl methacrylate).
  • the binder resin is a polymer of at least one ⁇ , ⁇ -alkanediol (for example, 1,4-butanediol and 1,6-hexanediol), at least one dibasic carboxylic acid (for example, fumaric acid), at least one st
  • the styrene-acrylic acid-based resin includes the third repeating unit derived from an acrylic acid-based monomer having an amino group and the fourth repeating unit derived from a styrene-based monomer.
  • the styrene-acrylic acid-based resin (the binder resin) is a cross-linked styrene-acrylic acid-based resin.
  • the styrene-acrylic acid-based resin is a polymer of at least one styrene-based monomer (for example, styrene), at least one aminoalkyl (meth)acrylate (specific examples include aminoethyl acrylate), and at least one cross-linking agent (for example, divinylbenzene).
  • styrene-based monomer for example, styrene
  • aminoalkyl (meth)acrylate specifically examples include aminoethyl acrylate
  • cross-linking agent for example, divinylbenzene
  • the toner mother particles may contain a colorant.
  • a known pigment or dye matching a color of the toner can be used as a colorant.
  • the amount of the colorant is preferably at least 1 part by mass and no greater than 20 parts by mass relative to 100 parts by mass of the binder resin.
  • the toner mother particles may contain a black colorant.
  • Carbon black can for example be used as a black colorant.
  • a colorant that is adjusted to a black color using a yellow colorant, a magenta colorant, and a cyan colorant can be used as a black colorant.
  • the toner mother particles may include a non-black colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.
  • the yellow colorant that can be used is for example at least one compound selected from the group consisting of condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and arylamide compounds.
  • yellow colorants that can be preferably used include C.I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 191, or 194), Naphthol Yellow S, Hansa Yellow G, and C.I. Vat Yellow.
  • the magenta colorant that can be used is for example at least one compound selected from the group consisting of condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.
  • magenta colorants that can be preferably used include C.I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, or 254).
  • the cyan colorant that can be used is for example at least one compound selected from the group consisting of copper phthalocyanine compounds, anthraquinone compounds, and basic dye lake compounds.
  • cyan colorants that can be preferably used include C.I. Pigment Blue (1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, or 66), Phthalocyanine Blue, C.I. Vat Blue, and C.I. Acid Blue.
  • the toner mother particles contain an ester wax as a releasing agent.
  • the amount of the ester wax in the toner particles is at least 8 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the non-crystalline polyester resin (the binder resin).
  • the ester wax in the toner particles has a dispersion diameter of at least 500 nm and no greater than 1,000 nm.
  • the releasing agent contained in the toner mother particles is substantially only an ester wax, in order to control releasability of the toner easily and reliably.
  • the ester wax is a synthetic ester wax.
  • the use of a synthetic ester wax as a releasing agent allows easy adjustment of the melting point of the releasing agent to within a desired range.
  • the synthetic ester wax can for example be synthesized through a reaction of an alcohol and a carboxylic acid (or a carboxylic acid halide) in the presence of an acid catalyst.
  • the raw materials of the synthetic ester wax may for example be derived from natural products (for example, a long-chain fatty acid produced from a natural oil or fat) or may be commercially available synthetic products.
  • the toner mother particles may contain a charge control agent.
  • the charge control agent is for example used in order to improve charge stability or a charge rise characteristic of the toner.
  • the charge rise characteristic of the toner is an indicator as to whether the toner can be charged to a specific charge level in a short period of time.
  • the anionic strength of the toner mother particles can be increased through the toner mother particles containing a negatively chargeable charge control agent (specific examples include organic metal complexes and chelate compounds).
  • the cationic strength of the toner mother particles can be increased through the toner mother particles containing a positively chargeable charge control agent (specific examples include pyridine, nigrosine, and quaternary ammonium salts).
  • a negatively chargeable charge control agent specifically examples include organic metal complexes and chelate compounds.
  • the cationic strength of the toner mother particles can be increased through the toner mother particles containing a positively chargeable charge control agent (specific examples include pyridine, nigrosine, and quaternary ammonium salts).
  • a positively chargeable charge control agent specifically examples include pyridine, nigrosine, and quaternary ammonium salts.
  • the toner mother particles may contain a magnetic powder.
  • materials of the magnetic powder that can be preferably used include ferromagnetic metals (specific examples include iron, cobalt, nickel, and alloys of any one or two of the aforementioned metals), ferromagnetic metal oxides (specific examples include ferrite, magnetite, and chromium dioxide), and materials subjected to ferromagnetization (specific examples include carbon materials made ferromagnetic through thermal treatment).
  • One magnetic powder may be used independently, or two or more magnetic powders may be used in combination.
  • An external additive (more specifically, a powder including a plurality of external additive particles) may be caused to adhere to the surfaces of the toner mother particles.
  • the external additive is not to be present inside of the toner mother particles but to be selectively present only on the surfaces of the toner mother particles (surfaces of the toner particles).
  • the toner mother particles (powder) and the external additive (powder) are stirred together, so that the external additive particles adhere to the surfaces of the toner mother particles.
  • the toner mother particles and the external additive particles do not react with one another and are physically, not chemically, connected to one another. Strength of the connection between the toner mother particles and the external additive particles can be adjusted depending on stirring conditions (specific examples include stirring time and rotational speed for stirring), the particle diameter of the external additive particles, the shape of the external additive particles, and a surface condition of the external additive particles.
  • the amount of the external additive is preferably at least 0.5 part by mass and no greater than 10 parts by mass relative to 100 parts by mass of the toner mother particles.
  • External additive particles are preferably inorganic particles, and particularly preferably silica particles or particles of a metal oxide (specific examples include alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate).
  • inorganic particles (powder) having a number average primary particle diameter of at least 5 nm and no greater than 30 nm are preferably used as the external additive particles.
  • particles of an organic acid compound such as a fatty acid metal salt (specific examples include zinc stearate) or resin particles may be used as the external additive particles.
  • composite particles which are particles of a composite of a plurality of materials, may be used as the external additive particles.
  • One type of external additive particles may be used independently, or a plurality of different types of external additive particles may be used in combination.
  • the external additive particles may be surface-treated.
  • a surface treatment agent that can be preferably used include coupling agents (specific examples include silane coupling agents, titanate coupling agents, and aluminate coupling agents), silazane compounds (specific examples include chain silazane compounds and cyclic silazane compounds), and silicone oils (specific examples include dimethylsilicone oil).
  • the surface treatment agent is a silane coupling agent or a silazane compound.
  • preferable silane coupling agents include silane compounds (specific examples include methyltrimethoxysilane and aminosilane).
  • preferable silazane compounds include HMDS (hexamethyldisilazane).
  • Table 1 shows toners (electrostatic latent image developing toners) TA-1 to TA-8 and TB-1 to TB-14 according to Examples and Comparative Examples.
  • “Non-crystalline PES” indicates non-crystalline polyester resin
  • “crystalline PES” indicates crystalline polyester resin
  • “S-Ac resin” indicates styrene-acrylic acid-based resin.
  • Table 2 shows S-Ac resins (styrene-acrylic acid-based resins) A to D used in production of the toners.
  • the following describes, in order, production methods, evaluation methods, and evaluation results of the toners TA-1 to TA-8 and TB-1 to TB-14.
  • an evaluation value was calculated by calculating an arithmetic mean of an appropriate number of measured values in order to ensure that any errors were sufficiently small.
  • glycerin was obtained through hydrolysis of palm oil, which is a vegetable oil. More specifically, palm oil and an aqueous sodium hydroxide solution having a concentration of 10% by mass in an amount twice an amount necessary to cause complete saponification of the palm oil were added into a reaction vessel. Next, the vessel contents were heated at 150° C. to cause complete saponification of the palm oil (vegetable oil). After the saponification, an aqueous glycerin solution was separated from the vessel contents, and the thus obtained aqueous glycerin solution was distilled. Glycerin obtained through the distillation was subjected to an activated carbon treatment to purify the glycerin.
  • a 5-L four-necked flask equipped with a stirrer (“SM-104”, product of AS ONE Corporation), a nitrogen inlet tube, a thermocouple, a drainage tube, and a rectification column was used as a reaction vessel.
  • SM-104 the plant-derived 1,2-propanediol
  • 1,743 g of terephthalic acid (carboxylic acid component) 1,743 g of terephthalic acid (carboxylic acid component), and 4 g of tin (II) dioctanoate (condensation catalyst) were added.
  • the vessel contents were caused to react at 230° C. for 15 hours under a nitrogen atmosphere at ambient pressure while removing water generated through the reaction. Thereafter, the internal pressure of the vessel was reduced to 8.3 kPa, and the vessel contents were caused to further react for 1 hour under conditions of a pressure of 8.3 kPa and a temperature of 230° C.
  • the internal pressure of the vessel was returned to ambient pressure, and the internal temperature of the vessel was reduced to 180° C. Subsequently, 288 g of trimellitic anhydride was added into the vessel. Next, the internal temperature of the vessel was raised up to 210° C. at a rate of 10° C/hour. Subsequently, the vessel contents were caused to further react for 10 hours at ambient pressure at 210° C. Next, the internal pressure of the vessel was reduced to 20 kPa, and the vessel contents were caused to further react for 1 hour under conditions of a pressure of 20 kPa and a temperature of 230° C.
  • the flask contents were caused to react for 1 hour under a reduced pressure atmosphere (pressure 8 kPa) at 210° C.
  • a reduced pressure atmosphere pressure 8 kPa
  • an ambient pressure atmosphere was regained, and 69 g of styrene (styrene-acrylic acid-based component) and 54 g of n-butyl methacrylate (styrene-acrylic acid-based component) were added into the flask.
  • the flask contents were caused to react at 210° C. for 1.5 hours.
  • the flask contents were caused to react for 1 hour under a reduced pressure atmosphere (pressure 8 kPa) at 210° C.
  • a reaction vessel equipped with a stirrer and a thermometer, 5,058 g of ion exchanged water, 22 g of a dispersant, 14 g of sodium sulfate, and 60 g of a defoaming agent (polyoxyalkylene pentaerythritol ether: “DISFOAM (registered Japanese trademark) CE-457”, product of NOF Corporation) were added.
  • a defoaming agent polyoxyalkylene pentaerythritol ether: “DISFOAM (registered Japanese trademark) CE-457”, product of NOF Corporation
  • the vessel contents were caused to react for 2 hours (more specifically, polymerization reaction of the vessel contents was promoted). Thereafter, the vessel contents were cooled to yield a dispersion containing a cross-linked styrene-acrylic acid-based resin.
  • the thus obtained dispersion was filtered (solid-liquid separation) through a metal mesh having a pore size of 2 mm to collect resin particles (powder). Next, nylon filter cloth was used to remove fines from the collected resin particles (powder). Thereafter, a washing process and a drying process were performed to yield a cross-linked styrene-acrylic acid-based resin (S-Ac resin A).
  • the S-Ac resins (cross-linked styrene-acrylic acid-based resins) B to D were obtained according to the same method as the synthesis of the S-Ac resin A in all aspects other than that the monomer blending ratio (aminoethyl acrylate/styrene) was changed so as to give the respective values of the amino group ratio shown in Table 2.
  • the amino group ratio in the S-Ac resins (cross-linked styrene-acrylic acid-based resins) A to D obtained as described above was measured, and results of the measurement are shown in Table 2.
  • the S-Ac resin A had an amino group ratio of 60%.
  • the amino group ratio was measured according to a method described below.
  • a Fourier-transform infrared spectrometer (“Frontier”, product of PerkinElmer Co., Ltd.) was used as a measuring device. The measurement was carried out in an attenuated total reflection (ATR) mode. Diamond (refractive index 2.4) was used as the ATR crystal.
  • the ATR crystal was attached to the measuring device, and 1 mg of a sample (any one of the S-Ac resins A to D) was placed on the ATR crystal.
  • the sample was pressed at a load of at least 60 N and no greater than 80 N using a pressure arm of the measuring device.
  • an FT-IR spectrum of the sample was measured under a condition of an infrared light incidence angle of 45°.
  • An intensity of a peak from the aromatic ring and an intensity of a peak from the amino group were determined from the resultant FT-IR spectrum.
  • the amino group ratio ratio of the intensity of the peak from the amino group to the intensity of the peak from the aromatic ring
  • An FM mixer (“FM-20B”, product of Nippon Coke & Engineering Co., Ltd.) was used to mix 100 parts by mass of the non-crystalline polyester resin (the non-crystalline polyester resin obtained as described above), the crystalline polyester resin (the crystalline polyester resin obtained as described above) in an amount shown in Table 1, a cross-linked styrene-acrylic acid-based resin (an appropriate one of the S-Ac resins A to D specified in Table 1 for the respective toners) in an amount shown in Table 1, a synthetic ester wax (“NISSAN ELECTOR (registered Japanese trademark) WEP-9”, product of NOF Corporation) in an amount shown in Table 1, 5 parts by mass of carbon black (“MA-100”, product of Mitsubishi Chemical Corporation), and 1 part by mass of a quaternary ammonium salt (“BONTRON (registered Japanese trademark) P-51”, product of ORIENT CHEMICAL INDUSTRIES, Co., Ltd.).
  • Toner TA-1 100 parts by mass of the non-crystalline polyester resin as described above, 30 parts by mass of the crystalline polyester resin as described above, 50 parts by mass of the cross-lined styrene-acrylic acid-based resin (the S-Ac resin A), 15 parts by mass of the ester wax (NISSAN ELECTOR WEP-9), 5 parts by mass of carbon black (MA-100), and 1 part by mass of the quaternary ammonium salt (BONTRON P-51) were mixed.
  • S-Ac resin A cross-lined styrene-acrylic acid-based resin
  • NPSSAN ELECTOR WEP-9 15 parts by mass of the ester wax
  • MA-100 carbon black
  • BONTRON P-51 1 part by mass of the quaternary ammonium salt
  • the resultant mixture was melt-kneaded using a twin screw extruder (“PCM-30”, product of Ikegai Corp.). Thereafter, the resultant kneaded product was cooled. The kneaded product (after cooling) was used as an evaluation target in pulverizing performance evaluation described below.
  • the kneaded product was coarsely pulverized using a pulverizer (“ROTOPLEX” (registered Japanese trademark)” product of Hosokawa Micron Corporation).
  • a pulverizer (“ROTOPLEX” (registered Japanese trademark)” product of Hosokawa Micron Corporation).
  • the resultant coarsely pulverized product was finely pulverized using a pulverizer (“Turbo Mill model RS”, product of FREUND-TURBO CORPORATION).
  • the resultant finely pulverized product was classified using a classifier (“Elbow Jet EJ-LABO”, product of Nittetsu Mining Co., Ltd.). As a result, toner mother particles having a volume median diameter of 7 ⁇ m were obtained.
  • FM-10B product of Nippon Coke & Engineering Co., Ltd.
  • AEROSIL registered Japanese trademark
  • RA-200H fine hydrophobic silica particles
  • EC-100 product of Titan Kogyo, Ltd.
  • substrate TiO 2 particles
  • coat layer Sb doped SnO 2 films, number average primary particle diameter: approximately 0.35 ⁇ m
  • the external additive adhered to the surfaces of the toner mother particles.
  • sifting was performed using a 300-mesh sieve (pore size 48 ⁇ m).
  • a toner (among the toners TA-1 to TA-8 and TB-1 to TB-14) including a plurality of toner particles was obtained.
  • the dispersion diameter of the releasing agent (ester wax) in the toner particles was measured.
  • Table 1 shows the measurement results.
  • the releasing agent had a dispersion diameter of 850 nm.
  • the dispersion diameter of the releasing agent was measured according to a method described below.
  • a sample (toner) was dispersed in a cold-setting epoxy resin and left to stand for 2 days at an ambient temperature of 40° C. to yield a hardened material.
  • the resultant hardened material was dyed in osmium tetroxide, and subsequently a flake sample having a thickness of 250 ⁇ m was cut therefrom using an ultramicrotome (“EM UC6”, product of Leica Microsystems) equipped with a diamond knife.
  • EM UC6 ultramicrotome
  • an image of a cross-section of the flake sample was captured using a scanning electron microscope (SEM) (“JSM-7401F”, product of JEOL Ltd., type: FE-SEM, FE electron source: a conical electron gun).
  • SEM scanning electron microscope
  • the SEM image (the image of the cross-section of the toner particle) was analyzed using image analysis software (“WinROOF”, product of Mitani Corporation) thereby to measure the dispersion diameter (equivalent circle diameter) of the releasing agent (ester wax).
  • WinROOF image analysis software
  • a number average dispersion diameter of releasing agent domains (ester wax domains) in the cross-section of the toner particle was calculated. More specifically, dispersion diameter measurement values of 100 releasing agent domains were obtained per image of a cross-section of one toner particle, and a number average dispersion diameter of the releasing agent domains in the cross-section of the toner particle was calculated based on the thus obtained 100 measurement values. Furthermore, such a number average dispersion diameter of releasing agent domains was obtained for cross-sections of 100 toner particles included in the sample (toner), and an arithmetic mean of the thus obtained 100 values was used as an evaluation value (releasing agent dispersion diameter) of the toner.
  • a 20-mL polyethylene container was charged with 20 g of the sample (toner), and a stress of 0.01 kgf/mm 2 was applied to the toner. With a stress of 0.01 kgf/mm 2 being applied to the toner in the container, the container was left to stand for 3 hours in a thermostatic chamber set at 25° C. Thereafter, the toner was taken out of the thermostatic chamber and used as an evaluation toner.
  • the thus obtained evaluation toner was placed on a 200-mesh sieve of known mass.
  • the mass of the toner on the sieve (mass of toner before sifting) was calculated by measuring the total mass of the sieve and the evaluation toner thereon.
  • the sieve was placed in a powder tester (product of Hosokawa Micron Corporation) and the evaluation toner was sifted in accordance with a manual of the powder tester by shaking the sieve for 30 seconds at a rheostat level of 5. After shifting, a mass of the toner that did not pass through the sieve (toner remaining on the sieve) was measured.
  • a degree of toner aggregation of no greater than 20% by mass was evaluated as “Good”.
  • a degree of toner aggregation of greater than 20% by mass was evaluated as “Not Good”.
  • a ball mill was used to mix 100 parts by mass of a developer carrier (carrier for FS-05200DN) and 5 parts by mass of the sample (toner) for 30 minutes to prepare a two-component developer.
  • a printer (“FS-05250DN”, product of KYOCERA Document Solutions Inc., modified to enable adjustment of fixing temperature) having a roller-roller type heat-pressure fixing device was used as an evaluation apparatus.
  • the two-component developer prepared as described above was loaded into a developing device of the evaluation apparatus, and the sample (toner for replenishment use) was loaded into a toner container of the evaluation apparatus.
  • the evaluation apparatus was used to form a solid image (more specifically, an unfixed toner image) having a size of 25 mm ⁇ 25 mm on evaluation paper (“COLOR COPY (registered Japanese trademark)”, product of Mondi, A4 size, basis weight 90 g/m 2 ) under conditions of a linear velocity of 105 mm/second and a toner application amount of 1.3 mg/cm 2 .
  • evaluation paper (“COLOR COPY (registered Japanese trademark)”, product of Mondi, A4 size, basis weight 90 g/m 2 ) under conditions of a linear velocity of 105 mm/second and a toner application amount of 1.3 mg/cm 2 .
  • the fixing temperature was set to within a range of from 100° C. to 150° C. to evaluate a minimum fixable temperature. More specifically, the fixing temperature of the fixing device was reduced in increments of a specific temperature from 150° C. to determine whether or not the solid image (toner image) was fixable at each fixing temperature. Thus, a minimum temperature at which the toner was fixable to the paper (a minimum fixable temperature) was measured. Determination of whether or not the toner was fixable was carried out through a fold-rubbing test described below. The evaluation paper passed through the fixing device was folded in half with a surface on which the image was formed facing inward and a 1 kg brass weight covered with cloth was rubbed back and forth on the fold with the image five times.
  • the paper was opened up and a fold portion (i.e., a portion on which the solid image was formed) of the paper was observed.
  • the length of toner peeling of the fold portion was measured.
  • the minimum fixable temperature was determined to be the lowest temperature among fixing temperatures for which the peeling length was no greater than 1 mm. Low-temperature fixability was evaluated as “Good” if the minimum fixable temperature was no greater than 130° C. and evaluated as “Poor” if the minimum fixable temperature was greater than 130° C.
  • a maximum fixable temperature was also measured within a fixing temperature range of from 150° C. to 250° C. More specifically, the fixing temperature of the fixing device was increased in increments of 2° C. from 150° C. to determine whether or not offset occurred at each fixing temperature. Thus, a maximum temperature at which offset did not occur (maximum fixable temperature) was measured. Determination of whether or not offset occurred was carried out through visual observation on the evaluation paper passed through the fixing device. More specifically, it was determined that offset had occurred if staining resulting from toner adhering to a fixing roller was observed on the evaluation paper. Hot offset resistance was evaluated as “Good” if the maximum fixable temperature was at least 200° C. and evaluated as “Poor” if the maximum fixable temperature was less than 200° C.
  • Table 3 shows evaluation results of the samples (the toners TA-1 to TA-8 and TB-1 to TB-14). Table 3 shows results of the evaluations of the low-temperature fixability (minimum fixable temperature), the hot offset resistance (maximum fixable temperature), and the degree of toner aggregation.
  • each of the toners TA-1 to TA-8 had the above-described feature. More specifically, the toner particles of each of the toners TA-1 to TA-8 contained a non-crystalline polyester resin and an ester wax (see Table 1). The toner particles of each of the toners TA-1 to TA-8 further contained at least 10 parts by mass and no greater than 30 parts by mass of a crystalline polyester resin and at least 30 parts by mass and no greater than 50 parts by mass of a styrene-acrylic acid-based resin relative to 100 parts by mass of the non-crystalline polyester resin (see Table 1).
  • the crystalline polyester resin included the first repeating unit derived from an acrylic acid-based monomer and the second repeating unit derived from a styrene-based monomer (see the section of “Synthesis of Crystalline Polyester Resin” above).
  • the styrene-acrylic acid-based resin included the third repeating unit derived from an acrylic acid-based monomer having an amino group and the fourth repeating unit derived from a styrene-based monomer.
  • the amino group ratio in the styrene-acrylic acid-based resin was at least 40% and no greater than 60% (see Tables 1 and 2).
  • the amount of the ester wax in the toner particles was at least 8 parts by mass and no greater than 15 parts by mass relative to 100 parts by mass of the non-crystalline polyester resin (see Table 1).
  • the ester wax (releasing agent) in the toner particles had a dispersion diameter of at least 500 nm and no greater than 1,000 nm (see Table 1).
  • the toners TA-1 to TA-8 showed excellent results in the low-temperature fixability evaluation, the hot offset resistance evaluation, and the degree of toner aggregation evaluation.
  • the toner TB-1 (the toner according to Comparative Example 1) showed poor results in the low-temperature fixability evaluation and the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the crystalline polyester resin was so large that dispersibility of the toner components (internal additives) was reduced.
  • the toner TB-2 (the toner according to Comparative Example 2) showed poor results in the low-temperature fixability evaluation and the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the releasing agent was so large that shear stress was insufficient during kneading of the toner components (the binder resin and the internal additives).
  • the toner TB-3 (the toner according to Comparative Example 3) showed a poor result in the hot offset resistance evaluation compared to the toners TA-1 to TA-8. It is thought that the amino group ratio in the styrene-acrylic acid-based resin was so small that compatibility between the binder resin and the ester wax (releasing agent) was excessively high (and thus the dispersion diameter of the releasing agent was excessively small).
  • the toner TB-4 (the toner according to Comparative Example 4) showed poor results in the low-temperature fixability evaluation and the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the styrene-acrylic acid-based resin was so large that dispersibility of the toner components (internal additives) was reduced.
  • the toner TB-5 (the toner according to Comparative Example 5) showed a poor result in the hot offset resistance evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the releasing agent was so small that releasability of the toner was insufficient.
  • the toner TB-6 (the toner according to Comparative Example 6) showed a poor result in the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amino group ratio in the styrene-acrylic acid-based resin was so large that compatibility between the binder resin and the ester wax (releasing agent) was insufficient, and thus the dispersion diameter of the releasing agent was excessively large.
  • the toner TB-7 (the toner according to Comparative Example 7) showed a poor result in the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the styrene-acrylic acid-based resin was so small that the dispersion diameter of the releasing agent was excessively large.
  • the toner TB-8 (the toner according to Comparative Example 8) showed poor results in the low-temperature fixability evaluation and the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the releasing agent was so large that dispersibility of the toner components (internal additives) was reduced.
  • the toner TB-9 (the toner according to Comparative Example 9) showed a poor result in the hot offset resistance evaluation compared to the toners TA-1 to TA-8. It is thought that the amino group ratio in the styrene-acrylic acid-based resin was so small that compatibility between the binder resin and the ester wax (releasing agent) was excessively high (and thus the dispersion diameter of the releasing agent was excessively small).
  • the toner TB-10 (the toner according to Comparative Example 10) showed poor results in the low-temperature fixability evaluation and the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the styrene-acrylic acid-based resin was so large that dispersibility of the toner components (internal additives) was reduced.
  • the toner TB-11 (the toner according to Comparative Example 11) showed a poor result in the hot offset resistance evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the releasing agent was so small that releasability of the toner was insufficient.
  • the toner TB-12 (the toner according to Comparative Example 12) showed a poor result in the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amino group ratio in the styrene-acrylic acid-based resin was so large that compatibility between the binder resin and the ester wax (releasing agent) was insufficient, and thus the dispersion diameter of the releasing agent was excessively large.
  • the toner TB-13 (the toner according to Comparative Example 13) showed a poor result in the degree of toner aggregation evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the styrene-acrylic acid-based resin was so small that the dispersion diameter of the releasing agent was excessively large.
  • the toner TB-14 (the toner according to Comparative Example 14) showed a poor result in the low-temperature fixability evaluation compared to the toners TA-1 to TA-8. It is thought that the amount of the crystalline polyester resin was so small that it was impossible to ensure sufficient low-temperature fixability of the toner.

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  • Chemical Kinetics & Catalysis (AREA)
  • Developing Agents For Electrophotography (AREA)
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180348655A1 (en) * 2017-05-31 2018-12-06 Kyocera Document Solutions Inc. Electrostatic latent image developing toner
US20220171304A1 (en) * 2020-11-27 2022-06-02 Sharp Kabushiki Kaisha Toner

Citations (1)

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JP2015004722A (ja) 2013-06-19 2015-01-08 コニカミノルタ株式会社 静電荷像現像用トナーおよびその製造方法

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JP3115063B2 (ja) * 1991-10-24 2000-12-04 株式会社リコー 静電荷像現像用正帯電性現像剤
JP3975105B2 (ja) * 2002-04-04 2007-09-12 三菱レイヨン株式会社 ポリエステル系トナー組成物
US8652728B2 (en) * 2010-10-18 2014-02-18 Konica Minolta Business Technologies, Inc. Toner for electrostatic latent image development and production method thereof
JP6023693B2 (ja) * 2013-11-28 2016-11-09 京セラドキュメントソリューションズ株式会社 トナー及びその製造方法
JP6440255B2 (ja) * 2014-12-16 2018-12-19 花王株式会社 電子写真用トナー
JP6392663B2 (ja) * 2014-12-26 2018-09-19 花王株式会社 電子写真用正帯電トナー
JP6520869B2 (ja) * 2016-08-31 2019-05-29 京セラドキュメントソリューションズ株式会社 静電潜像現像用トナー

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JP2015004722A (ja) 2013-06-19 2015-01-08 コニカミノルタ株式会社 静電荷像現像用トナーおよびその製造方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180348655A1 (en) * 2017-05-31 2018-12-06 Kyocera Document Solutions Inc. Electrostatic latent image developing toner
US10394147B2 (en) * 2017-05-31 2019-08-27 Kyocera Document Solutions Inc. Electrostatic latent image developing toner
US20220171304A1 (en) * 2020-11-27 2022-06-02 Sharp Kabushiki Kaisha Toner

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